public MessageBoxSample() {
HorizontalPanel buttons = new HorizontalPanel();
buttons.setSpacing(4);
SimpleButton button = new SimpleButton("Show Error");
button.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
String title = "The Error";
String message = "This is the content of the message and it's very long to see how it copes with it";
MessageBox.show(NotificationType.ERROR, MessageBox.OptionType.OK, title, message, new MessageBox.OptionCallback() {
public void handle(MessageBox.Button button) {